Russians break into Kupiansk via gas pipeline

Russian forces recently attempted to advance behind Ukrainian positions in Kupyansk via an underground gas pipeline — the third time Russian forces have used this tactic so far in the war. Russia’s repeated use of this tactic further indicates that Russian forces are improving their ability to disseminate tactical lessons between various sectors of the front line. A Ukrainian military intelligence (GUR)-affiliated source reported on September 12 that Russian forces entered a gas pipeline from a wooded area near Lyman Pershyi (northeast of Kupyansk), traveled through the pipe for an estimated four days with electric scooters and modified wheeled stretchers, and exited the pipe near Radkivka (immediately north of Kupyansk).[

The Ukrainian source reported that Russian forces then advanced toward Kupyansk and the nearby railway line. The Ukrainian General Staff acknowledged that Russian forces conducted the mission and stated that Russian forces are accumulating on the northern outskirts of Kupyansk but have not entered Kupyansk itself. The commander of a Ukrainian drone regiment operating in the Kupyansk direction stated that Ukrainian forces have since struck and damaged the pipeline and that Russian forces are no longer able to advance through the pipeline.[3] Russian milbloggers claimed that it is unclear when Russian forces conducted the mission, and some claimed that Russian forces may have advanced through the gas pipeline in early September 2025, indicating that the footage may be up to a week and a half old.[4] Kupyansk Military Administration Head Andriy Besedin stated on September 13 that Russian forces do not currently hold positions in Kupyansk but that fighting is ongoing near the outskirts of the city.

Russian forces previously leveraged underground pipelines to advance behind Ukrainian defensive positions in Avdiivka, Donetsk Oblast in January 2024 and in Sudzha, Kursk Oblast in March 2025. Elements of the Russian 60th Veterany Separate Assault Brigade (Volunteer Assault Corps) reportedly participated in both of the gas pipeline missions in Avdiivka and Sudzha.[6] ISW has not observed reports of the brigade operating in the Kupyansk direction, indicating that the Russian military command is disseminating the brigade’s knowledge and success in such missions to other units and formations. ISW noted in January 2025 that the Russian military command appeared to be at least attempting to improve its ability to disseminate lessons learned, given that Russian forces are exhibiting similar operational patterns across the front line.[7] Alternatively, the use of pipelines to enable infiltration may be more reflective of individual Russian units’ on-the-spot tactical innovation and adaptation in the face of proliferated Ukrainian drone capabilities, as such pipelines provide Russian forces with natural cover and concealment that can enable forward movement.

The international community continues to condemn the recent Russian drone incursion into Poland’s airspace. Polish Deputy Foreign Minister Marcin Bosacki presented a joint statement at the United Nations (UN) on September 12, in which nearly 50 countries denounced Russia’s incursion into Polish airspace on the night of September 9 to 10 with 19 drones.[8] Bosacki stated that Russia purposely violated Poland’s territorial integrity and trespassed against NATO and the EU. Ukrainian Permanent Representative to the UN Andriy Melnyk stated that Ukraine shares Poland’s view that the Russian drone incursion was not a technical error, but rather a deliberate act aimed at escalating tensions and testing the international community’s response to ongoing Russian aggression. Melnyk warned leaders that Russia may continue to escalate if the international community fails to respond decisively. US Acting Permanent Representative to the UN Dorothy Shea reiterated that the United States remains committed to defending “every inch of NATO” and noted that Russia’s incursion undermines the ongoing US efforts to broker an end to Russia’s war in Ukraine. Shea stated that Russia has intensified its air campaign against Ukraine following the US-Russia Alaska Summit on August 15 and that such actions demonstrate “immense disrespect for good faith US efforts” to usher in peace. ISW has also observed a marked intensification in Russia’s long-range strikes against Ukraine since mid-August 2025.[9] Shea conveyed that the United States is urging Russia to negotiate directly with Ukraine to demonstrate its seriousness in seeking an immediate end to hostilities and to prevent Russia’s war from expanding.

Russian and Belarusian officials continue to deflect responsibility for Russia’s recent drone incursion into Polish airspace. Russian Permanent Representative to the UN Vasily Nebenzya claimed on September 12 that Poland “hastened to place the blame on Russia without presenting any evidence linking Russia to the incident.”[10] Nebenzya denied that the drones used in the incursion could be of Russian origin because the range of the drones found in Poland does not exceed 700 kilometers. Nebenzya claimed that Russia “expressed its readiness for a professional dialogue” with Poland after the incursion. Nebenzya proceeded to shift blame onto the West and accused European countries of using the Russian incursion into Polish airspace to spread “an information campaign” aimed at increasing support for Ukraine and guaranteeing new arms deliveries. The Russian Ministry of Foreign Affairs claimed on September 12 that Russia “refuted the speculations… about plans to attack one of the NATO countries” and that such speculations could lead to “an inevitable escalation,” which Russia does not want. Belarusian Chargé d’Affaires of the Permanent Mission to the UN Artem Tozik claimed that Poland’s accusations against Belarus’ involvement in the drone incursion are “baseless,” and that Belarus was the first to inform Poland about the approach of drones that “went off course” during the overnight Russian strikes against Ukraine.

Additional information about the Russian drone incursion undermines Nebenzya’s and Tozik’s statements, however. Sky News published an image on September 11 of one of the Russian Gerbera drones that landed in Poland, and Bosacki shared an image at the UN Security Council meeting showing Cyrillic letters on one of the drones.[13] Ukrainian outlet Militarnyi analyzed Sky News’ image and determined that the Russian drone was equipped with an Iranian-made Tallysman satellite navigation four-channel controlled reception pattern antenna (CRPA).Militarnyi reported that CRPAs filter out false signal sources from electronic warfare (EW) systems in order to make the drone more resistant to EW. The presence of CRPAs indicates that it is unlikely that these Russian drones flew off course due to EW jamming. The September 9 to 10 incursion of at least 19 drones in a single night is notable and is roughly three times the number of projectiles that have breached Polish airspace during the entirety of Russia’sfull-scale invasion. It is extremely unlikely that such a concentrated number of drones could have violated Polish airspace accidentally or due to technical or operator error. ISW has observed other evidence refuting Russian and Belarusian denials, including evidence that the drones had fuel tanks that increased their range to as far as 900 kilometers.